Generally, a spring having a small spring constant is used to provide a comfortable vehicle ride. However, the spring having a small spring constant causes the vehicle to roll at an angle toward the outside of the wheel in a turn as a result of a centrifugal force. For this reason, vehicles with independent suspension use an anti-roll bar to reduce wheel rolling and maintain balance of a car body during a turn.
The anti-roll bar is an auxiliary spring that institutes a spring action according to a stroke difference between left and right wheels during rolling. The anti-roll bar is a C-shaped, bent steel rod of which its central part is used as a torsion bar while both ends are respectively fastened to left and right suspension arms. The anti-roll bar does not function as a spring while the left and right wheels are in simultaneous vertical movement. However, when the left and right wheels are respectively in opposite vertical movement or have different strokes, the anti-roll bar reduces inclination of the car body via a spring force generated by a torsion action.
However, there is a drawback in the anti-roll bar thus described in that left and right anti-roll bars are connected to each other, such that road shock to one side of the wheel is transmitted to the other side during a vehicle roll and during an independent ascent or descent of the left or the right wheel as well, thereby reducing the ride comfort and steering of a vehicle.